Operators of electronic commerce systems, advertising networks, content delivery networks, or any system in which content is delivered may wish to know more information about users. Some users, particularly in the context of the Internet in which users are communicating with a system via a browser, mobile application, or the like, can be effectively anonymous to the operator of the system. That is to say, the user may not be associated with a user account or identity for which demographic information is known. Accordingly, in such a scenario, targeting users with relevant content can be difficult, as the system does not possess any demographic or other information on which to base targeting decisions.